Bagmaking machine

ABSTRACT

A bagmaking machine comprises pairs of pressure rollers for applying contact pressure to the end portions of continuously conveyed bag workpieces, which end portions are to be adhered. At least on one side of the plane in which the workpieces are conveyed the pressure rolls consist of a plurality of disc-shaped rolls, the axes of which are offset in the direction of travel and which have an axial length each amounting only to a fraction of the width of the bag end portion. The disc-shaped rolls are offset transversely to the direction of travel in such a manner that the ranges of action of the discs taken together cover the entire area of the workpiece end portion.

United States Patent [72] inventors Fritz Achelpohl;

Herbert Schmedding, Lengerich of Westphalia, Germany [21] Appl. No. 703,134 [22] Filed Feb. 5, 1968 [45] Patented Jan. 12, 1971 [73] Assignee Windmoller & Holscher Westphalia, Germany [32] Priority Feb. 21, 1967 [33] Germany v [31] No. W43408 [54] BAG-MAKING MACHINE l 1 Claims, 8 Drawing Figs.

[52] US. Cl 93/8, 100/176 [51] Int. Cl B3lb l/00 [50] Field of Search 93/8, 8VB;

[5 6] References Cited UNITED STATES PATENTS 2,635,973 4/1953 Swindler 100/ l76Y 3,043,199 7/1962 Niemeyer 93/8 Primary Examiner-Bernard Stickney Attorney-Fleit, Gipple & Jacobson ABSTRACT: A bag-making machine comprises pairs of pressure rollers for applying contact pressure to the end portions of continuously conveyed bag workpieces, which end portions are to be adhered. At least on one side of the plane in which the workpieces are conveyed the pressure rolls consist of a plurality of disc-shaped rolls, the axes of which are offset in the direction of travel and which have an axial length each amounting only to a fraction of the width of the bag end portion. The disc-shaped rolls are offset tra nsversely to the direction of travel in such a manner that the ranges of action of the discs taken together cover the entire area of the workpiece end portion.

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- to be'sealed against'the adjacent parts BAG-MAKING MACHINE This invention relates to a bagmaking machine which comprises pairs of pressure rollers for applying contact pressure to the end portions of continuously conveyed bag workpieces, which end portions are to be adhered.

In the manufacture of bags, particularly of bags having crossed ends, from packaging materials which are impermeable or have a low permeability to air', such as impregnated or plastic-coated papers or nonwoven fabrics, or sheeting of polyethylene or polyvinylchloride, the surfaces to be adhered with contact adhesive must be subjected to a high contact pressure for a short time. The contact pressure for bonding sheetlike packaging materials with contact adhesive is applied either as two-dimensional pressure, e.g., with press tools, or as linear pressure, e.g., between pairs of rolls. A two-dimensional pressure cannot be applied in the continuous manufacture of bags so that only linear pressure between two pressure rolls can be used. In known manner, one roll is mounted in sta-' tionary bearings, and the other roll is movable against spring pressure. In the manufacture of bags from the above-menpackaging material. This effect is due to the fact that the packaging material is impermeable to air or its permeability to airis not sufiicient for a rapid escape of air, in combination with the fact that the contactpressure causes the end portion of the bag so that the air cannot escape into said adjacent parts. Q

The folding results in an overlap of parts of the end portion so that the number of plies in the end portion varies, e.g., in a e.g., bag having an end patch, the number of plies varies between three and nine. For this reason it is not possible to subject all parts of the adhered end portion to the required, uniform linear pressure between two cylindrical rolls, even if the rolls are covered with rubber having an optimum Shore hardness. This has been shown by experience.

Finally, the application of linear pressure between pairs of rolls, particularly to elastic plastics material, causes a buildup of material opposite to the direction of travel of the workpiece before the roll nip. This buildup of material can be compared to the bow wave of a ship and results in a wrinkling of the material at the termination of the end portion so that the latter does not retain its correct shape. This phenomenon will be referred to hereinafter as a fulling effect.

It is an object of the invention to enable the manufacture of satisfactory crossed end bags in different sizes, which are adhered with contact adhesive, and to accomplish this with extremely simple means and in a continuous process while changeover times are avoided. It is another object of the invention to avoid a compression of the air which is enclosed in the bag end portion during the application of pressure and to prevent the above-mentioned fulling effect consisting in the detrimental buildup of material before the point where the pressure is applied.

To accomplish these objects in a bagmaking machine of the kind mentioned first hereinbefore, it is proposed according to the invention that at least on one side of the plane in which the workpieces are conveyed the pressure rolls should consist of a plurality of disc-shaped rolls, the axes of which are offset in the direction of travel and which have an axial length each amounting only to a fraction of the width of the bag end portion and which are offset transversely to the direction of travel in such a manner that the ranges of action of the discs taken together cover the entire area of the workpiece end portion.

Thus, the conventional pair of pressure rolls are replaced by a which are offset in the working direction.

As a result of the invention, a compression of the air which is enclosed in the bag end portion is avoided because the air can escape between the discs into the adjacent parts of the end portion, which adjacent parts have previously been subjected to contact pressure or will subsequently be subjected to contact pressure. The air is thus pressure-relieved.

The use of a multiplicity of narrow discs also facilitates the application of uniform pressure to a crossed end having a varying number of plies because each disc works on a narrow strip and is not adversely affected by more elevated portions outside said strip so that each disc is forced by the pressure spring against the bag end portion under the optimum contact pressure. Whereas steps in the material which extend obliquely to the direction of travel will be subjected to contact pressure in a stepped pattern, the width of a step corresponds only to the small width of the disc whereas with a continuous roll the width of the step is determined by the entire length of the oblique step in the material so that no contact pressure is applied to a large area having a smaller number of plies. The

height of the step will increase with the obliquity of the step in the material relative to the direction of travel. The arrangement according to the invention results in an application of pressure approximately in an area having the desired size.

The fulling effect which is always present during the application of pressure to elastic-plastic material is substantially reduced by the use of a plurality of discs, which are offset in the direction of travel, as is taught by the invention. The builtup material can spread to the right and left before the disc. The direction of displacement is reversed at the succeeding disc. The overall result is a wavelike displacement of the material in the rolling plane. The larger the number of discs,

the smaller is the extent of the wavelike displacement of material in a plane.

In order to apply an even more uniform contact pressure and to avoid a fulling effect even in the triangular pockets of crossed end portions, which pockets are not to be adhered, it is a further feature of the invention to provide the pressure discs in the form of pressure area-defining discs, which have a circumference equal to the length in which pressure is to be applied. This may be most simply accomplished in that the discs are provided on their peripheries with recesses which define the area in which pressure is to be applied. An additional control device is then required to ensure that the material to be processed is fed to the contact pressure rolls at an exactly predetermined point of the cycle. It is also necessary in this case always to replace the discs when the size of the bag end portions to be made on the bagmaking machine is to be changed. For this reason it is more desirable according to the invention if the circumference of the discs is equal to the length of the longest bag end portions to be made on the bagmaking machine and the discs are provided with means for securing to their peripheral surfaces a replaceable covering which corresponds to the desired pressure area. In this case it is sufficient to replace the covering for a change in the size of the bag or its end portion. The covering which corresponds to the desired pressure area consists suitably of rubber or an elastomer having an optimum Shore hardness so that the covering will properly conform to the slight surface irregularities which are inevitable in any bag end portion. Experience has shown that in such case the pressure applied decreases from the middle of the disc along the contact pressure line toward the edges, particularly where elastic material is being processed. For this reason it will be an advantage where the above-described covering which corresponds to the pressure area is used if the ranges of action of the individual pressure discs slightly overlap each other. This overlap may also be beneficial in other cases.

For a further reduction of the fulling effect, the pressure discs and the rolls cooperating therewith are driven in accordance with the invention. Without such drive, a pulling device would be required to move the material to be processed in the direction of travel. The tension applied by a pulling device would promote the fulling effect because the pressure applied by the rolls and discs produces a frictional force at right angles to the direction of pressure if there is a transport in this direction. The frictional force is always opposite to the direction of travel and depends on the travelling material and on the surface of the rolls and discs. This frictional force is particularly high with elastic-plastic material. A pulling device would obviously stretch elastic material on the tension side and would constrict it at right angles to that direction. The contact pressure force and the frictional force in the contact zone result in a buildup of material on that side of the nip which is opposite to the tension side. The abovedescribed frictional reaction force will not be produced if the discs and rolls are driven. The backing rolls which cooperate with the pressure discs have preferably a larger axiallength than the individual pressure discs. To facilitatethe manufacture and the adjustment, all backing elements which cooperate with the pressure discs consist preferably of elongated rolls of the same size. It has also been found that the fulling effect will no longer be produced to a detrimental extent in such an arrangement if the backing rolls are disposed on that side of the plane of travel to which the bag end portions are folded so that the pressure discs roll on the smooth rear side of the bag workpieces, which rear side is formed by a bag wall.

According to the invention, the advantages of an application of pressure to an area having a desired size can be obtained even where no pressure area-defining discs are used if the pressure discs are movable from a position of rest to an operative position and back in dependence on the movement of the bag workpieces past the discs. In that case, relatively small discs of equal size and having no pressure area-defining recess can be used and these discs will be lifted when they have rolled over the trailing edge of the end patch and will be lowered as soon as the leading edge of a new patch enters the pressure area. This lifting and lowering can be effected with known control means.

The offset of the disc shafts in the direction of travel is determined by the radius of the discs. The transverse offset of the discs is determined by the width of the discs. If the disc shafts should be spaced as closely as possible in order to reduce the space requirement, the strips to be rolled cannot overlap, for the reasons stated. In view of this fact it is a feature of the invention that only one pressure disc is carried by each pressure disc shaft, the spacing between the pressure disc shafts is less than a pressure disc diameter, a first set of pressure discs extending from one lateral margin of a bag end portion to the other is succeeded by a second set of pressure discs, the number of which is smaller by one than those cf the first set, and the radial center plans planes of the discs of the second set coincide with the center planes of the spaces between the discs of the first group.

The discs of the second set roll over the nonrolled strips between adjacent rolled strips and slightly overlap the latter.

Where small pressure discs are used so that the space consideration is not so important, each pressure disc shaft suitably carries two pressure discs, the distances between corresponding end faces of the pressure discs on each shaft is one-half of the width of the bag end, the spacing of the pressure disc shafts is larger than the diameter of the pressure discs, the discs have the same width and successive pairs of discs are relatively staggered transversely to the direction of travel by not more than the width of a pressure disc. Such an arrangement facilitates the manufacture because all pressure disc shafts with the pairs of pressure discs thereon are alike and it is sufficient to arrange them in laterally staggered positions.

The invention will be described hereinafter with reference to two embodiments shown by way of example in the drawing, in which FIG. 1 is a diagrammatic sectional view showing a bag to which patches have been applied, which are to be adhered.

FIG. 2 is a side elevation showing a contact pressure-applying station according to a first embodiment of the invention.

FIG. 3 is a sectional view taken on line III-III of FIG. 2 thrnlwh a nrecedin preliminary pressure-applying station.

FIG. 4 is a sectional view taken on line IV-IV in FIG. 2 through one of the pressure discs and the associated backing roll.

FIG. 5 is a longitudinal sectional view taken on line V-V in FIG. 2 through the contact pressure-applying station containing a bag workpiece.

FIG. 6 is a side elevation showing a contact pressure-applying station according to a second embodiment of the invention.

FIG. 7 is a sectional view taken on line VII-VII of FIG. 6

through a pair of pressure discs and the backing roll associated therewith.

FIG. 8 is a longitudinal sectional view taken on line VIII-VIII of FIG. 6 through the contact pressure-applying stution containing the bag workpiece.

All gears, idlers, rolls and discs which will be mentioned hereinafter are eorotationally mounted on their respective shafts and the latter are rotatably mounted in the frames or frame parts or in bearings mounted in cm guides. A simpler bearing arrangement is possible for idlers. They may be rotatably mounted on axles which are nonrotatably clamped in the side cheek of the outer frame. The drive gear I transmits rotation to the gears 2 and 3. The gear 2 is in mesh with the gear 4. The gear 3 is in mesh with the gear 5 and the idler 7. The latter is in mesh with the gear 8, which drives the gears 9 and 11. All gears and idlers shown, including the gear 28, are driven in this way.

It is apparent from FIG. 3 that the roll 2 rotates with the gear 2 because both are pinned to one and the same shaft, which is mounted at one end in a side cheek 29 of the outer frame and at the other end in a frame member 30.

The gears 2 and 4 interrnesh, as has been described. The roll 4' rotates with the gear 4 and is formed in the middle with a peripheral recess. The gear 4 and the roll 4' are pinned to a shaft, which is mounted in cam guides 6 and 6. The cam guides consist of a slider, cam slot, pin and spring and are secured at one end to the side cheek 29 of the outer frame and at the other end to the side check 31 of the inner frame. The cam guide provides a yieldable mounting of the lower part of the preliminary pressure-applying device.

FIG. 4 can be understood from the description of FIG. 3. In FIG. 4, the recessed roll 4 is replaced by a narrow disc 9', which has a covering 9" corresponding to the area in which pressure is to be applied. The cam guide is designated 10. The discs 13', 16, 19, 22, 25' and 28' are mounted just as the disc 9' but are laterally offset, as is apparent from FIG. 5. Each of said discs is provided with a covering that corresponds to the covering 9" and has the same length as the zone to be adhered (end patch). The backing rolls which correspond to the roll 8' have all the same length, which is at least as large as the width of the end patch.

As is apparent from FIG. 5, the roll 4 is succeeded by a rotatably mounted, driven disc 5, which covers the width of the recess in the roll 4'. Both rolls serve only for an application of preliminary contact pressure.

Whereas cam guides are shown only for the rolls 4 and discs 9, they are in fact provided for all rolls and discs disposed below the section plane V-V.

The frame member 30 is firmly connected to the side cheek 29 of the outer frame by carrying arms, which are not shown. As a result, there is a space between the frame member 30 and the side check 31 of the inner frame for the travel of the bag workpieces to be processed.

The means shown in FIGS. 3, 4 and 5 are arranged with mirror symmetry on the other side of the bagmaking machine.

The contact pressure-applying station which has been described hereinbefore has the following mode of operation. The bag 32 shown in FIG. I having crossed ends 33 and 34 and unadhered end patches 35 and 36 passes through the preliminary pressure-applying station 2, 4', in which the end patches lying loosely on the respective crossed ends are subjected to slight contact pressure. Any enclosed air can escape because the preliminary pressure roll 4 has a recess. The bag passes then between the roll 3 and disc 5', where it is subjected to contact pressure in the area where the preliminary pressure-applying roll 4' was ineffective. During this operation, the air can escape into zones which are disposed outside the strip contacted by the disc.

The end patch is subjected to a very high contact pressure in the main contact pressure-applying station. The application of contact pressure begins ina strip having the same width as the disc 9 and terminates in a strip having the same width as the disc '28. The results which are thus obtained have been described hereinbefore. The length of the contact pressureapplying station is determined by the width of the disc.

The second embodiment shown in FIGS. 6 to 8 comprises a preliminary pressureapplying station which is identical to the preliminary pressure-applying station described last hereinbefore and for this reason will not be described in detail once more. In the side elevation of FIG. 6, the side check of the outer frame has been omitted. There are pairs of pressure discs 44,44 to 48,48 and each of these pairs cooperate with backing rolls 39 to 43. Each of the rolls 39 to 43 are secured to a shaft 49 for rotation therewith (FIG.'7). Each shaft 49 has also a gear 50 secured to it for rotating the shaft. Each of the discs 44,44 0 48,48 "is firmly connected to a gear 51,51; Each of the gears 51,51 is rotatably mounted in an arm 52 or 52' of a two-armed rocker lever 53 or 53. Each rocker lever 53 or 53 is rotatably mounted on the hub of a gear 54.or 54.

Each of the gears -54 and 54" is secured to a shaft 55 or 56 to 59, which is rotatably mounted in the machine frame. The gears 54 and 54 mesh with the gears 51 and 51. Each of the shafts 55 to 59 has also a-gear 60 to64 secured to it, which serves for rotating the respective shaft 55 to 59.

The pressure discs 44,44 to 48,48 and the backing rolls 39 to 43 are driven by a drive gear 65 (FIG. 6) via an idler 66 and the gear 60, which rotates the shaft 55 for driving the discs 44 and 44'. The rotation of the gear 60 is transmitted by an idler 67 to the gear 61 so that the shaft 56 for driving the discs 45,45 is rotated. The rotation of the gear 61 is transmitted by an idler 68 to the gear 50 for driving the backing roll 39. The furtherbacking rolls 40 to 43 are driven by additional idlers 69 to 71, which rotate the respective gears 50. The idlers 69 to 71 rotate also the gears 62 to 64 for driving the other pressure discs46,46 to 48,48. 7

Tension springs 72 and 72 are stretched between short pins onthe lever arms .of 53 and 53' and pins shown only in FIG. 6 and secured to the side cheek 73 of the inner frame. By-these tension springs, the discs are firmly pressed against the respective backing rolls. The pressure discs are yieldable because the levers 53,53 are rotatably mounted on the hubs the gears 51,51. The relations discussed with reference to FIG. 7 are the same in all other sections which can be conceived on lines VII-VII in FIG. 6, except that the positions of the pairs of shafts 77 in such a manner that the rocker levers 53,53 are jected to high contact pressure between the rolls and the pairs of small, narrow discs. The contact pressure is initially applied in strips having the width of 44 and 44 and terminates in strips having the width of 48 and 48'. Known control devices ensure -that the discs are firmly pressed against the associated rolls only'within the area of the end patch. Outside this area, the

discs are lifted bv the eccentrics. In FIG. 8, the pairs of discs 44 and 45 apply high contact pressure whereas the pair of discs 46 and the succeeding discs are still lifted. When the application of pressure by the pair of discs 46 begins, the pair of discs 44 begin to lift. In this way the fulling'effect in the triangular pockets is entirely avoided, as has been described hereinbefore. I

The hatched triangle 78 on the disc 46 indicated that a lower contact pressure is applied in this zone than in the rest ,of the strip rolled over by the disc 46. Because the step in the triangular zone. On the other hand, the length of the contact pressure-applying zone is inversely proportional to'the width of the contact pressure-applying discs. I

We claim:

1. In a machine for making bags having adhered end portions folded on to one side of, the bags and being conveyed along a predetermined path of travel, means for pressing said end portions, said pressing means comprising a plurality of pressing discs having an axial length each amounting only to a fraction of the width of said end portion and being spaced in the direction of said path of travel and offset transversely-to said path of travel such that the ranges'of action, of said pressing discs taken together cover the entire area of said end portion, and a plurality of backing rolls cooperatingwith said pressing discs, each of said backing rolls having an axial length greater than that of one of said pressing discs.

2. A machine as defined in-claim 1, wherein said backing rolls are arranged along said path of travel such thatthey face that side of the bags said end portions are folded to.

3. A machine according to claim 1, comprisingo'ne shaft for each of said pressing discs, the spacing of said shafts being smaller than one pressing disc diameter, and wherein a first set of pressing discs extending from one lateral margin of the bag end portion to the other is succeeded by a second set of pressing discs, the number of pressing discs of said second set being smaller by one than that of said first set, and the radial center planes of the discs of said second set coinciding with the center planes of the spaces between the discs of said first set.

4. A bagmaking machine according to claim 1, characterized in that the circumference of the discs corresponds to the length of the longest bag end portion to be made on the bagmaking machine and the discs are provided with means for securing to their peripheral surfaces a replaceable covering which defines the pressure ares.

5. A bagmaking machine according to claim 4, characterized in that the covering which defines the pressure area consists of rubber or an elastomer.

6. A bagmaking machine according to claim 1, characterized in that the ranges of action of the discs overlap.

7. A bagmaking machine according to claim 1, characterized in that the pressure discs and their backing rolls are provided with a drive means.

8. A bagmakingmachine according to claim 1, characterized in that the pressure discs are movable from a position of rest to an operative position and vice versa in dependence on the passage of the bag workpieces.

9. A machine according to claim 1, comprising a plurality of shafts for carrying said pressing discs, each of I said shafts carrying at least two pressingdiscs, the spacing of theend faces of said pressing discs on each of said shafts being at most onehalf of the width of the bag end portion, the spacing of said .shafts exceeding the diameter of said pressing discs, and suc- 11. A machine as defined in claim 10, wherein each of said other arm of said lever being connected to the respective one pressing discs is mounted in one arm of a two-armed lever of said tensioning means.

rotatably mounted on the respective one of said shafts, the 

1. In a machine for making bags having adhered end portions folded on to one side of the bags and being conveyed along a predetermined path of travel, means for pressing said end portions, said pressing means comprising a plurality of pressing discs having an axial length each amounting only to a fraction of the width of said end portion and being spaced in the direction of said path of travel and offset transversely to said path of travel such that the ranges of action of said pressing discs taken together cover the entire area of said end portion, and a plurality of backing rolls cooperating with said pressing discs, each of said backing rolls having an axial length greater than that of one of said pressing discs.
 2. A machine as defined in claim 1, wherein said backing rolls are arranged along said path of travel such that they face that side of the bags said end portions are folded to.
 3. A machine according to claim 1, comprising one shaft for each of said pressing discs, the spacing of said shafts being smaller than one pressing disc diameter, and wherein a first set of pressing discs extending from one lateral margin of the bag end portion to the other is succeeded by a second set of pressing discs, the number of pressing discs of said second set being smaller by one than that of said first set, and the radial center planes of the discs of said second set coinciding with the center planes of the spaces between the discs of said first set.
 4. A bagmaking machine according to claim 1, characterized in that the circumference of the discs corresponds to the length of the longest bag end portion to be made on the bagmaking machine and the discs are provided with means for securing to their peripheral surfaces a replaceable covering which defines the pressure ares.
 5. A bagmaking machine according to claim 4, characterized in that the covering which defines the pressure area consists of rubber or an elastomer.
 6. A bagmaking machine according to claim 1, characterized in that the ranges of action of the discs overlap.
 7. A bagmaking machine according to claim 1, characterized in that the pressure discs and their backing rolls are provided with a drive means.
 8. A bagmaking machine according to claim 1, characterized in that the pressure discs are movable from a position of rest to an operative position and vice versa in dependence on the passage of the bag workpieces.
 9. A machine according to claim 1, comprising a plurality of shafts for carrying said pressing discs, each of said shafts carrying at least two pressing discs, the spacing of the end faces of said pressing discs on each of said shafts being at most one-half of the width of the bag end portion, the spacing of said shafts exceeding the diameter of said pressing discs, and successive ones of said discs being staggered laterally to said path of travel by at most the width of one of said pressing discs.
 10. A machine as defined in claim 9, wherein each of said pressing discs is yieldably mounted on the respective one of said shafts by separate tensioning means.
 11. A machine as defined in claim 10, wherein each of said pressing discs is mounted in one arm of a two-armed lever rotatably mounted on the respective one of said shafts, the other arm of said lever being connected to the respective one of said tensioning means. 